Just for some clarification did your mean iPad 2 (released 2011) or iPad Air 2 (the newest model)?

Either way, I recommend you turn off your device, or do a hard rest (press the side lock button and home button at the same time until the Apple logo appears).

You may have to update your device to the latest release in order to download the app updates. Some developers require a certain version of the operating system in order for the app to function as intended.